Attempts are being made to obtain the toxic component(s) from Listeria monocytogenes by various extraction procedures which are routinely used for the preparation of endotoxins from gram-negative organisms. The materials so obtained will be purified by column, thin layer and gas chromatography followed by chemical analyses in an effort to determine their chemical make up. In addition, biological activities of the isolated component(s) such as pyrogenicity, skin reactivity and lethality will be evaluated. The data obtained on the chemical analyses and the biological activities of the component(s) will be compared with that of a classical endotoxin.